New Crystal Structure Map for Intermetallic Compounds

金属间化合物的新晶体结构图

基本信息

批准号：
03650575
负责人：
MORINAGA Masahiko
金额：
$ 1.28万
依托单位：
Toyohashi University of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1991
资助国家：
日本
起止时间：
1991 至 1992
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03650575/
关键词：
Intermetallic Compounds Crystal Structure Electronic Structure Molecular Orbital Method

项目摘要

New crystal structure maps were proposed based on the calculation of electronic structures by the discrete variational (DV)-Xalpha cluster method. Two electronic parameters were utilized in order to construct such a map for aluminides and silicides containing transition metals, M. The one was the bond order that is a measure of the covalent bond strength between M and Al(or Si) atoms. The other was d orbital energy level which correlated with the atomic size and electronegativity of elements. For example, structure maps pertinent to MAl, M_3Al, MAl_3, MSi, M_3Si, MSi_2 and M_5Si_3 were made using these two theoretical parameters. There was clear separation of crystal structures in every map. It was found that these new maps were more accurate in predicting the crystal structures of the compounds than any other structure maps so far developed (for example, the Pettifor map ).Furthermore, structure maps which are usable even for ternary compounds were constructed by taking into account the substitutional sites of third elements in binary compounds. Employing the maps for five intermetallic compounds, TiAl, Nb_3Al, NiAl, FeAl and MoSi_2, the possibility of changing their crystal structures was examined by the addition of third elements into binary compounds. It was concluded that these new structure maps were useful for the design and development of new intermetallic compounds.

基于离散变分（DV）-Xalpha簇法的电子结构计算，提出了新的晶体结构图。使用两个电子参数来构建包含过渡金属 M 的铝化物和硅化物的图。其中一个是键级，它是 M 和 Al（或 Si）原子之间的共价键强度的量度。另一个是d轨道能级，它与元素的原子尺寸和电负性相关。例如，使用这两个理论参数制作了与MAl、M_3Al、MAl_3、MSi、M_3Si、MSi_2和M_5Si_3相关的结构图。每张图中晶体结构都有明显的分离。结果发现，这些新图在预测化合物的晶体结构方面比迄今为止开发的任何其他结构图（例如 Pettifor 图）更准确。此外，通过以下方法构建了甚至可用于三元化合物的结构图：考虑二元化合物中第三种元素的取代位点。利用TiAl、Nb_3Al、NiAl、FeAl和MoSi_2五种金属间化合物的图谱，考察了通过在二元化合物中添加第三种元素来改变它们晶体结构的可能性。结论是，这些新的结构图对于新型金属间化合物的设计和开发很有用。